The Loudoun County Sheriff's Office has called off its search for a 40-year-old Bowie man who was reported missing Wednesday after he failed to pick up his 9-year-old daughter from a baby sitter.

Police say that despite two days of searching, including the use of trained dogs and a Fairfax County helicopter, they have no leads in the disappearance of John Frank Cirios of the 8400 block of Spruill Drive and have classified the case as "suspicious."

"We just don't know what happened," said Sgt. Terry McCracken of the sheriff's office.

Police said Cirios, whom they described as a responsible and punctual person, was last seen Wednesday at 5 p.m. at the Alban Tractor Co. on Sully Road in Sterling, where friends say he worked as a trouble-shooter.

That evening, Cirios failed to pick up his daughter from a baby sitter in Bowie. Police said that Cirios had not lived with his wife for some time and that he had custody of the child.

On Thursday morning Cirios failed to report to work, and coworkers noticed that his vehicle had not moved from the parking lot, police said.

In Bowie, Cirios is known as a generous neighbor who spent most of his spare time working on his house and caring for his daughter.

Four area churches said prayers for him yesterday morning, including the Bowie United Methodist Church, where Cirios frequently attended services.

Pastor William Nelson described Cirios as an exceptionally loving father and as a solid member of the community. "You could depend on him," Nelson said.

Carol Mints, who lives near Cirios, said he was a talented mechanic and always punctual. "You could set your clock by him," she said. "And, he just completely adored his child. This is out of character."

The two-day search, which ended Saturday, was conducted in an approximately two-square-mile area around the tractor plant, police said.

Although the plant is about one-half mile from the Washington & Old Dominion trail where another missing person, jogger Judith DeMaria, was last seen in August, police said there is no apparent connection between the two cases.

Police said Cirios wore tan slacks and a jacket that said "Alban" and "John" on it. He is described as 5 feet 11 inches tall and 140 pounds, with brown hair, brown eyes and eyeglasses.